Circuit breaker



Dec. 14, 1937. A. J H M 2,102,295

CIRCUIT BREAKER Original Filed March 6, 1933 2 Sheets-Sheet 1 INVENTOR BY W T t/W,

Dec. 14, 1937. J THOMSON 2,102,295

CIRCUIT BREAKER Original Filed March 6, 1933 2 Sheets-Sheet 2 ATTORNEY.

Patented Dec, 14, 1937 PATENT OFFICE CIRCUIT BREAKER Alfred J. Thomson, Detroit, Mich, assignor to Bulldog Electric Products Company, Detroit, Mich, a corporation of West Virginia Application March 8, 1933, Serial No. 659,714

. APR 1 1941 Renewed January 11, 1937 22 Claims. (Cl. 200-116) This invention relates to circuit breakers, and principally aims to provide a novel form 01 circuit breaker, such as will be particularly described with reference to the appended drawings.

The breaker herein disclosed is provided with a novel operating mechanism which forms the principal novel feature thereof and the provision of which is a principal object of the invention.

Among the characteristics of the breaker disclosed in the drawings, are the following:

(1) The breaker is trip free; that is to say, upon release of the breaker parts by the overload release element, the breaker parts will trip and move to their overload released position, even though the handle, which normally operates the breaker, is held against movement intentionally or accidentally; the breaker parts trip for overload release, free of the handle.

(2) The breaker is so constructed as to have quick make and break action on normal operation, and quick-break action on overload release, and these actions are accomplished even though a relatively small number of parts are used in the breakers.

(3) The connection between the operating handle and the breaker parts, though permitting quick make and break, is positive, so that even though the springs which provide the quick make and break action should become injured, or prove insuflicient to cause make and break, or so that even though the contacts stick, make and break can be accomplished positively by movement oi. the handle.

(4) The operating springs are in the nature of compression springs, which is of advantage,'due to the fact that compression springs are more satisfactory of operation than other forms of springs.

(5) Further, the compression springs are mounted on links so that in-the event a spring breaks, the broken parts will not fall into and among the live parts of the breaker, with consequent damage.

(6) Further, the operating compression springs are so positioned and connected that they need be flexed only a relatively small distance, as contrasted with other breakers, wherein considerable flexng of the springs is' required, it being observed that lessening of the required spring-flexinghas the effect of prolonging the life of the springs.

(7) Further, the springs are not connected to the operating handles, and therefore, the handles can be moved, for positive make and break, independently of the springs.

(8) Further, reset action, after overload oflf' 25 in link i5, receiving a pin 26 of link 22.

tripping, can be accomplished without the contact arm moving out of off position, this insuring that the circuit will not be closed, even momentarily, on reset. Further, the parts are so constructed that the reset action includes a snap action, to insure quick and positive reset.

Still further objects will readily occur to those skilled in the art upon reference to the following description and the accompanying drawings in which Figs. 1-3 are plan, elevation, and end views, respectively of a circuit breaker, shown in on position;

Figs. 4 and 5 show the device in oif position and overload off position, respectively.

The device of Figures 1-5 In Figures 1 to 5 there is shown a circuit breaker having three positiofis, on (Fig. 2), switch "012 (Fig. 4) and overload off" (Fig. 5).

The device includes a base i0 having a pair of contacts H which are to be engaged by the contacts i2 on the ends of a resilient bridging contact arm l3. One of the contacts I i is connected to the line, and the other is connected to one leg of the thermostatic or bi-metallic warping element It, the other leg of the latter being connected to the load. When the contact arm i3 is in on position, current flows through contacts II and I2, contact arm l3 and warping element ll.

To the vertically moving contact arm I3 is rigidly secured an upwardly projecting sliding link l5 and a downwardly projecting guide plate i6, these being insulated from arm I3, as shown.

The lower end of the guide plate l6 slides between two spring jaws ll of a lower guide block l8 firmly fastened to base Ill. The sides of the sliding link l5 snugly fit into an upper guide block l9 rigidly secured to a vertical front plate 2|.

, A link 22 is pivotally connected at 23 to a horizontal link 24 and is slidably connected to the upper end of link l5, through an elongated slot A coiled compression resisting spring 21 is mounted on the right hand end of link 24, between a pin 28 thereon and the bight of a U-shaped, horizontally positioned spring compression link 28, which is pivotally connected at 3| to a pawl 32, the latter being pivotally connected by shouldered screws 33 on its left hand end to front plate 21 and vertical back plate 43a. As indicated, the link 24 passes through a slot in the bight of link 29, and these links move as a unit, around pivot 3|. In the on position, the right hand or free end 35 or Russuu) 2 vpawl 32 is held downby a tongue-36 of warping element l4.

The left hand end 31 of link 24 is pivotally connected to an operating bell crank 38 by a pin 39, the latter sliding in an arcuate slot 4| of the crank. The bell crank has an extension 42 forming an operating handle for the device, and is pivotally supported on the cross shaft 43, the latter connecting front plate 2| and the vertical back plate 43a.

The parts just described may be operated as a simple, quick make and break switch as follows: Assume the parts to be in on position (Figure 2). When the handle 42 is moved to the right, the bell crank 38 rotates clockwise, carrying end '31 of link 24 along with it, thus moving links 24 and 29, together, about the pivot 3|, clockwise. This action pulls link 24 to the left a slight degree and builds up an increased compression in coil springs 21. All this while, the link 22 and its pin 26 travels the length of the slot 25 in sliding link I5, and link l and arm l3 do not move, link l5 being held by spring jaws l1 frictionally engaging guide part It.

As soon as link 24 has passed over center (shaft 43) the coil spring operates, to move links 24 and 29 further past shaft 43, with a snap action, thus pulling contact -arm l3 to its off position, for a quick break of the circuit, slot 4| permitting snap action movement of links 24 and 29, independently of the handle 42, so that quick break may be effected independently of the operator.

Handle 42 is so connected that it may move the sliding link 5, without the assistance of the spring 21, after having taken up the lost motion provided in slots 25 and 4|. This permits the handle 42 to move the bridging arm l3 positively to the o position, and permits the operator to free the contacts |2 in case they should stick, and to move the switch positively to the ofi position, independently of the spring, in the event the spring should become broken or weakened too much to function of its own accord.

The bell crank 38 may be moved to the extreme "off position as limited by the engagement of the reset lug 44 and stop 45 on pawl 32.

Reverse movement of handle 42, to the left, from the off position (Fig. 4) imparts a counter-clockwise movement to link 24 about pin 3|. This action pulls link 24 to the left and compresses spring 21 between pin 28 and the bight of the spring compression link 29, until link 24 is past center (shaft 43).

All this while, the link 22 and its pin 26 travels the length of the slot 25 in sliding link i5, and link I5 and arm I3 do not move, being held by spring clips l1 frictionally engaging guide part l6. Then the compressive force of the spring reacts, giving a rapid counter-clockwise movement to link 24, forcing down link 22, sliding link l5, and arm l3, until the circuit is completed through contacts II and I2.

Slot 4| permits a snap action movement of links 24 and 29, independent of the movement of handle 42, in order to eflect a quick make, independent of the operator. The bell crank may be moved to the extreme on position, as determined by the length of slot 4|, and the on position of link 24, as shown in Fig. 2.

The action just described is a quick make action, and takes place when spring 21 functions properly. At other times, the positive connection between handle 42 and link l5, as previously described, insures contact making.

During switch operation, travel of pawl 32,

about its pivot screws 33 is prevented, by its end 35 being held by the tongue 36 of warping element l4.

It will be observed that slot 4| provides a lost motion connection between handle 42 and link 24, which permit movement of the latter, when overcenter and as influenced by spring 21, independently of the handle for accelerating the quick make and break action of the linkage 24, 22, I5, etc., the extent of this action being determined by the dimensions of slot 4| and the associated parts. A positive make and break action of the linkage is, however, assured by the positive (even though lost motion) connection between handle 42 and link 24.

The foregoing parts, in conjunction with other parts to be described below, serve to move contact arm from on" position to a second or overload oif position, when element l4 warps to the right due to an overload in the line, and also serve to enable the operator to reset the switch after it had been tripped on overload, by moving the various parts, linkages, and the pawl 32 from their overload off position to their normal oif position without causing contact arm l5 to close the circuit and these operations are carried on as follows:

Assume the switch to be in on position. When the element l4 warps (to the right) its tongue 38 releases pawl end 35, permitting the compression in spring 21 to tend to move link 29, and consequently pin 3|, to the left. Since pin 29 is :fixed to pawl 32 at 3|, the movement of pin 3| to the left is on an arc whose center is pivot 33, and is necessarily accompanied by an upward movement of pin 3|. The parts move up and their inertia carries them to the point where pawl 32 is engaged by the hooked ledge 41 on stop 48. By this time, the line of action of spring 21, thru a line connecting pivot 39 and pin 29, is above center 43, and the spring therefore causes drum 38 to rotate clockwise, to pull the left end of link 24 clockwise, and to pull pin 23 upwardly. This movement, operating through links 22 and i5, raises contact arm |3 to the position shown in Figure 5, known as overload off, for breaking the circuit. Quick break is of course assured by the action of spring 21.

In view of the fact that this action can take place without interference from handle 42, due to the fact that the pivot 39 does not move on this action, the breaker cannot be prevented from tripping, merely by holding handle 42 so that pivot 39 can not move. In other words, the breaker will trip even though the handle be held. This characteristic places the breaker in the trip-free class.

When the parts are to be reset, that is to say, when contact arm I3 is to be moved from overload off (Fig; 5) to switch ofi (Fig. 4), handle 42 is moved to the right, rotating bell crank 38 clockwise until the lower edge of elongated slot 4| comes in contact with pin 39 carrying it past center (shaft 43). The spring 21 then continues the clockwise movement of pin 39 pivoting link 24 about pin 3| until shoulder 52 on spring compression link 29 engages shoulder 53 on link 24.

A continued movement of the handle to the right causes the stop lug 44 on bell crank 38 to engage stop on pawl 32, rotating the latter clockwise about screws 33 until its end 35 snaps under tongue 36 of warping element f4, resetting the parts to the switch "01f" position of Figure 4;.

.By properly proportioning and connecting the parts, the action may be such that during movement of the handle 42, lug 44 can be resetting link 32 to its normal latched position, during the time that link 24 is moving overcenter to the "01! position.

It will be seen that the position of the contact arm I! does not change while the other parts move from overload off position to switch "01! position (reset position). Accordingly, there is no danger of the circuit being closed, even momentarily, until the breaker is under the control of the warping element l4.

It will be observed at this time that the breaker described in the foregoing possesses certain novel and desirable characteristics. It is trip-free; it operates with a quick make and break action, both on normal switch operations, and on overload; it insures positive make and break, in addition to and without interfering with the quick make and break; and it can be resetafter tripping, with a snap action.

In addition, in the event the spring 11 breaks, it will not fall into the live parts of the breaker, with consequent damage, but will remain upon the link 24 upon which it is mounted, being held between pin 28 and link 29.

Further, since the spring 21 does not have to be flexed to any great extent, due to the tangential relation of the link 21 and the drum 38, the life of the spring is relatively prolonged.

Further, it is to be noted that this circuit breaker employs only one spring for all its operations, this spring serving to perform the functions of quick make and quick break under normal switching, and quick break under overload tripping.

Further, since the spring 21 connects the operating link 24 and the pawl, it is free of the handle, and therefore does not interfere with positive make and break action of the handle, as contradistinguished from constructions wherein the spring connects the operating link or part to the handle.

Now having described one form of breaker, reference will be had to the following claims which determine the scope of the invention, it being expressly understood that the breaker heretofore described and disclosed has been chosen merely as an example, and not as illustrating all of the possible embodiments of the invention.

- I claim:

1. In a circuit breaker of the character described, an operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost-motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl.

2. In a circuit breaker of the character described, an operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the spring providing a quick make and break movement for the breaker parts controlled by the operating link,

3. In a circuit breaker of the character described, an operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said releasepart and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the aforesaid links moving about the connection between the spring compression link and the pawl, as a pivot, with the pawl at rest, during normal make and break operation.

4. In a circuit breaker of the character described, an operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connections of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally conr nected to the operating link and to the pawl, the links moving'about the connection between the spring compression link and the pawl, as a pivot, with the pawl at rest, during normal make and break operation, the spring providing a quick make and break movement for the breaker parts controlled by the operating link.

5. In a circuit breaker of the character described, an operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the operating link and the pawl together .moving about their adjacent pivotal connections as pivots, on overload release movement.

6. In a circuit breaker of the character de-- scribed, an operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the DIV-,-

otal connection of the pawl, a compression spring A on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the operating link and the pawl together moving about theirradjacentpivotal connections as pivots on overload .release movement, the spring providing a quick make and break movement for the breaker parts controlled by the operating link.

7. In a circuit breaker of the character described, an operating mechanism including an elongated pawl fixedly pivoted at one end to a fixed part, and normally held down at the other end by an overload release part, an operating crank fixedly pivoted to a fixed part and having a reset part for engaging said pawl and resetting it by moving it downwardly after it has been released by said release part and moved upwardly, an operating link connected at one end to said crank by a positive, lost motion pivotal connection and positioned alongside said pawl, with its aforesaid pivotal connection adjacent the pivotal connection of the pawl, a compression spring on the end of said operating link adjacent the release part, and a spring compression link pivotally connected to the operating link and to the pawl, the links moving about the connection between the spring compression link and the pawl, as a pivot, with the pawl at rest, during normal make and break operation, the operating link and the pawl together moving about their adjacent pivotal connections as pivots, on overload release movement.

8. In a circuit breaker, a linkage comprising parallel elongated links, a movable connection 4 which is pivotally secured to one link and is movable along and engages the other and which connects the links, said other and engaged link being provided with resilient means disposed between an end thereof and the connection, holding means at opposite ends of said linkage for holding said linkage in normal position, and a contact operatively connected to the linkage, the linkage normally being so held by the holding means that the resilient means thereof is in a condition wherein it has potential energy stored therein,

and constantly tends to vary the distance between the connection and one of the holding means and to shift the linkage, movement of one of said holding means releasing the linkage and permitting the resilient means to expend its potential energy and shift the linkage about the other holding means and at the same time to vary the distance between the connection and the first holding means, so as to provide a snap action movement of the linkage and a snap release of the contact. v

9. In a circuit breaker, a linkage comprising parallel elongated links, a movable connection which is pivotally secured to one link and is movable along and engages the other and which connects the links, said other and engaged link being provided with resilient means disposed between an end thereof and the connection, hold ing means at opposite ends of said linkage for holding said linkage in normal position, and a contact operatively connected to the linkage, the linkage normally being so held by the holding means that the resilient means thereof is in a condition wherein it has potential energy stored therein, and constantly tends to vary the distance between the connection and one ofv the holding means and to shift the linkage, one of said holding means being manually movable, movement of that holding means releasing the linkage and permitting the resilient means to expend its potential energy and shift the linkage about the other holding means and at the same time to vary the distance between the connection and the first holding means, so as to provide a snap action movement of the linkage and a snap release of the contact.

10. A construction of the character described in claim 8, wherein both anchorages are movable, with one manually controlled and the other controlled by the circuit current so as to move on overload.

11. In a circuit breaker, a linkage comprising parallel elongated links, a movable connection which is pivotally secured to one link and is movable along and engages the other and which connects the links, said other and engaged link being provided with resilient means disposed between an end thereof and the connection, holding means at one end of said linkage for holding said linkage in normal position, a movably mounted handle operatively connected to the linkage near the end thereof remote from the holding means, a contact operatively connected to the linkage, the linkage normally being so held that the resilient means is in a condition wherein it has potential energy stored therein and constantly tends to shift the linkage and vary the distance between the connection and the holding means, movement of the handle shifting the linkage to a position wherein subsequent release thereof from manual control will permit the resilient means to expend its potential energy and shift the linkage about the holding means and vary the distance between the connection and the holding means with a snap aczion to provide a snap action release of the con- 12. A construction of the character described in claim 11 wherein the handle is rotatably mounted and wherein movement of the handle shifts the linkage across and over the center of rotation of the handle, whereupon the resilient means expands its energy to continue shifting of the linkage but with a snap action.

13. A construction of the character described in claim 11 wherein the handle is rotatably mounted and wherein movement of the handle up to its over center position shifts the linkage and also energizes the resilient means and wherein movement of the handle across its over center position places the linkage in position to' be moved further, but with a snap action, by the resilient means when the handle is released.

14. A construction of the character described in claim 11 wherein the holding means is responsive to circuit conditions so as to release on overload and permit the resilient means to shift the linkage about the handle and vary the length I connecting the handle to the link and so conamass-a of the variable length part thereof with a snap action to provide a snap action release of the contact.

15. A construction of the character described in claim 11 wherein the holding means is responsive to circuit conditions so as to release on overload and permit the resilient means to shift the linkage about the handle and vary the length of the variable length part thereof with a snap action to provide a snap action release of the contact, the handle being movable thereafter to reset the thus released linkage into a position wherein it is held by the holding means.

16. In a circuit breaker, a frame, a link, means pivotally mounting the link thereon, a handle pivotally mounted on the frame, means pivotally structed and arranged as to enable the link to slide circularly about the pivotal mounting of the handle, the handle being operable to slide the link circularly about the pivotal mounting of the handle, a contact controller, means connecting it to the link, a spring operatively connected to the link in such a manner that it will oppose movement of the link out of one position, the spring being positioned to be stressed by and on movement of the link out of that position and to move the link with a snap action into another position when so stressed and when the link has been moved partially out of the first position and towards such other portion by the handle.

1'7. In a circuit breaker, a frame, a link, means pivotally mounting the link thereon, a handle pivotally mounted on the frame, means pivotally connecting the handle to the link and so constructed and arranged as to enable the link to slide circularly about the pivotal mounting of the handle, the handle being operable to slide the link circularly about the pivotal mounting of the handle, a contactcontroller, means connecting it to the link, a spring operatively. connected to the link in such a manner that it will oppose'movement of the link out of one posi-v tion,'-the spring being positioned'to be stressed by and on movement of the link out of that position and to move' the link with a snap action into another position when so stressed and when the link has been moved partially out of the first positionand towards such other portion by the handle, and means for automatically releasing the pivotal mounting for the link on a circuit abnormality to release the link and permit the spring to move it about its pivotal connection to the handlefor circuit interruption.

18. A circuit breaker including a movable mechanism, a contact, means operatively connecting the contact to the movable mechanism whereby movement of the mechanism causes movement 01' the contact, a handle, means pivotally mounting the handle, means operatively connecting the handle to the mechanism whereby movement of the handle causes movement viding separate holding means for the mechanism, the spring, the latch, the mechanism, and the handle being so constructed and arranged and relatively located that on release of the latch the spring biases the mechanism to open circuit position by moving it around the handle as a pivot without moving the handle, and on movement of the handle the spring biases the mechanism to open circuit position by moving it around the latch as a pi lb't WithoutihWing the latch, the points of connection between the handle and the mechanism and between the latch and the mechanism being spaced from each other.

19. In a. circuit breaker controlling mechanism, a resilient mechanism, a movable current responsive latch so constructed and arranged that it normally engages the mechanism for holding it, the parts being so arranged relatively that the mechanism, when held by the latch, is under longitudinal stress, the latch being movable on a circuit abnormality for releasing the mecha nism, a rotatably mounted handle, means operatively connecting it to the mechanism, the hendle being so constructed and arranged that on rotary movement thereof out of its normal position it will stress the mechanism longitudinally and move it bodily out of its normal position and towards the center of rotation of the handle so that when the handle is released after such movement the mechanism will tend to relieve itself of the longitudinal stress created therein by such movement of the handle with a snap action, the parts being so arranged relatively that on such stress relieving movement of the mechanism following such handle movement and subsequent release, the mechanism will move bodily beyond the center of rotation of the handle and about the connection between the mechanism and latch as a pivot, and also being so arranged relatively that. on release of the latch, when the handle and mechanism are in normal position, the mechanism will tend to relieve itself of the stress that it possesses when it is held by the latch with a snap action and in so doing will move bodily about its connection to the handle as a pivot.

20. A construction of the character described in claim 18 wherein the handleis so arranged relatively to the contact that it may be manipulated to reset the contact, following movement thereof responsive to release of the latch, by movement of the handle in a manner generally similar to the movement thereof that causes movement of the link about the latch as a pivot.

21. A construction of the character described in claim 19, wherein the handle is so arranged relatively to the mechanism that it may be manipulated to reset the mechanism into normal position and held by the latch under stress, following movement thereof responsive to release of the latch, by movement of the handle in a manner generally similar to the movement thereof that causes movement of the mechanism out of normal latch held position.

22. A construction of the character described in claim 19 wherein the points of connection between the handle and mechanism and between the latch and mechanism are spaced from each other.

ALFRED J. THOMSON. 

